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Risk Management Activities - Maximum exposure to credit risk (Details) - CAD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Disclosure of credit risk exposure [line items] |  |
Maximum exposure to credit risk | $ 22 | $ 5
Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Maximum exposure to credit risk | 1,555 |
Credit risk | Trade and other receivables |  |
Disclosure of credit risk exposure [line items] |  |
Maximum exposure to credit risk | $ 583 |
Trade and other receivables | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |
Trade and other receivables | Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 92.00% |
Trade and other receivables | Non-Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 8.00% |
Long-term portion of finance lease receivable | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |
Maximum exposure to credit risk | $ 228 |
Long-term portion of finance lease receivable | Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |
Long-term portion of finance lease receivable | Non-Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 0.00% |
Risk management assets | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |
Maximum exposure to credit risk | $ 692 |
Risk management assets | Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 93.00% |
Risk management assets | Non-Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 7.00% |
Amortized cost | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |
Maximum exposure to credit risk | $ 52 |
Amortized cost | Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 0.00% |
Amortized cost | Non-Investment Grade [Member] | Credit risk |  |
Disclosure of credit risk exposure [line items] |  |
Credit risk, allocation percentage | 100.00% |

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- Definition The amount that best represents the maximum exposure to credit risk without taking into account any collateral held or other credit enhancements (for example, netting agreements that do not qualify for offset in accordance with IAS 32). [Refer: Credit risk [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2019-01-01 -Paragraph 35K -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2019-en-r&anchor=para_35K_a&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2021-01-01 -Name IFRS -Number 7 -IssueDate 2019-01-01 -Paragraph 36 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_36_a&doctype=Standard&book=b -URIDate 2019-03-27 + Details
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- Definition Credit Risk, Allocation Percentage + References No definition available. + Details
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- Details
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